fstyp(1M)

NAME
     fstyp - determine filesystem identifier

SYNOPSIS
     fstyp special

DESCRIPTION
     fstyp allows the user to determine the filesystem identifier of mounted
     or unmounted filesystems using heuristic programs.  The filesystem type
     is required by mount(2) and sometimes by mount(1M) to mount filesystems
     of different types.

     The directory /etc/fstyp.d contains a program for each filesystem type to
     be checked; each of these programs applies some appropriate heuristic to
     determine whether the supplied special file is of the type for which it
     checks.  If it is, the program prints on standard output the usual
     filesystem identifier for that type and exits with a return code of 0;
     otherwise it prints error messages on standard error and exits with a
     nonzero return code.

     fstyp runs the programs in /etc/fstyp.d in alphabetical order, passing
     special as an argument; if any program succeeds, its filesystem type
     identifier is printed and fstyp exits immediately.  If no program
     succeeds, fstyp prints "Unknown_fstyp" to indicate failure.

WARNING
     The use of heuristics implies that the result of fstyp is not guaranteed
     to be accurate.

SEE ALSO
     mount(1M), mount(2), sysfs(2).